The newly engaged pair — joined by another couple and their toddler — was all smiles in the center of the restaurant’s atrium room. Timberlake, 31, looked handsome in a blue-and-white checkered short-sleeved shirt and newsboy cap, and Biel, 30, was gorgeous in an aqua dress, cream blazer, little makeup and her hair in a high ponytail.

Biel’s ring — which she’s rarely flashed in public since her and Timberlake’s engagement was announced in January — features a large, slightly rounded square-cut diamond with smaller stones surrounding it, and appears to have a vintage feel.

An onlooker tells PEOPLE that during the meal, Timberlake and Biel sat side by side, noshed on sandwiches and were very sweet with each other, as well as with their friends’ child — and that the actress “could not have looked happier.” Tell us: What do you think of Biel’s engagement ring?